Cand compilez programul de mai jos imi apar urmatoarele erori:
undefined reference to ‘WinMain@16’
error: ld returned 1 exit status

#include <stdlib.h>

using namespace std;

class Fraction
{
private:
int num, den;
public:
void set(int n, int d)
{
num=n;
den=d;
normalize();
}
int get_num()
{
return num;
}
int get_den()
{
return den;
}
private:
void normalize();
int gcf(int a, int b);
int lcm(int a, int b);
};

void Fraction::normalize()
{
if(den==0||num==0)
{
num=0;
den=1;
}
if(den<0)
{
num *= -1;
den *= -1;
}
int n=gcf(num, den);
num=num/n;
den=den/n;
}

int Fraction::gcf(int a, int b)
{
if(a%b==0)
return abs(b);
else
return gcf(b, a%b);
}

int Fraction::lcm(int a, int b)
{
return (a/gcf(a,b))*b;
}

Multumesc anticipat pentru ajutor!